There has already been known a vessel filling system for filling a vessel with liquid or like after sterilization of the vessel by the irradiation of electron beam (refer to Japanese Patent Application Laid-open Publication No. 2006-314407). This publication discloses an electron beam irradiation sterilization system provided with an introduction chamber R0, a pre-sterilization chamber R1, a sterilization chamber R2 for performing electron beam sterilization, a rinser chamber R3 blowing air in a vessel, a filling chamber R4 for filling the vessel with inner content, and a capping chamber R5 for applying a cap to a vessel, which are arranged in this order from an upstream side in a vessel conveying direction.
In the sterilization chamber in which the vessel is sterilized by the irradiation of the electron beam, ozone is generated every time the electron beam irradiation. The vessel subjected to the electron beam irradiation is transferred from the sterilization chamber R2 to the rinser chamber R3 with the ozone remaining inside, and when air is blown into the vessel in the rinser chamber R3, the ozone is pushed out of the vessel.
In order to prevent the ozone pushed out of the vessel from flowing into the sterilization chamber R2 arranged upstream side thereof and the filling chamber R4 arranged downstream side thereof, in the invention of the above Patent Publication 1, a pressure P2 in the sterilization chamber R2, a pressure P3 in the rinser chamber R3 and a pressure P4 in the filling chamber R4 are controlled so as to satisfy an relation of P3<P2<P4. That is, the pressure P3 in the intermediately arranged rinser chamber R3 is lowest, the pressure P2 in the sterilization chamber R2 arranged upstream side of the rinser chamber R3 is higher than the pressure P2, and the pressure P4 in the filling chamber R4 arranged downstream side of the rinser chamber R3 is further higher than the pressure P2 in the sterilization chamber R2.    Patent Publication 1: Japanese Patent Application Laid-open Publication No. 2006-314407